Pfizer has discontinued a Phase III trial assessing the potential of Sutent (sunitinib malate) in combination with prednisone for men with advanced castration-resistant prostate cancer after yet another disappointing performance by the drug.

The world’s number one drugmaker said last night that an interim analysis of data indicates that the combination is unlikely to improve overall survival compared to prednisone alone in men whose disease had progressed despite treatment with a docetaxel-based chemotherapy regimen.

“There is a great need for better therapies for prostate cancer and we are committed to working with basic scientists and clinical researchers to identify more effective treatments for this disease,” said Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs, Pfizer Oncology Business Unit, commenting on the decision.

Sutent (sunitinib) is an oral multi-kinase inhibitor currently on the market for the treatment of gastrointestinal stromal tumor (GIST; if patients are intolerant or become resistant to imatinib mesylate), and advanced/metastatic renal cell carcinoma, and the company is also currently assessing its potential as an adjuvant treatment of renal cell carcinoma in a late-stage trial.

But the drugmaker’s major clinical programme for Sutent has waned considerably over the last year or so. In 2009, Pfizer discontinued a Phase III trial of the drug in colorectal cancer after it failed to offer a significant progression-free survival benefit, and this was followed by further failures in breast, liver and lung cancers, substantially curtailing its potential indications.

As before, Pfizer said no new safety issues had been uncovered in the failed study.